Cerebrospinal fluid was obtained in healthy men at different ages for evaluation of products and precursors of brain neurotransmitters and of proteins and electrolytes. Computer assisted tomography (CT) was applied to healthy men at different ages, and analyzed by quantitative image processing techniques. Even in healthy men, brain atrophy occurs in the elderly. Gray matter volume is correlated negatively with age whereas cerebrospinal fluid volume is correlated positively with age.